Biometrics allows a person to be identified and authenticated based on a set of recognizable and verifiable data, which are unique and specific to them. Biometric authentication includes the process of comparing data for a person's characteristics to that person's biometric “template” to determine resemblance. Biometric authentication systems can be grouped based on the physical characteristic employed to authenticate users. Examples of such systems include authentication based on fingerprints, hand geometry, palm veins, retina scans, iris scans, facial recognition, signatures, and voice analysis.